1. Field of the Invention
The present invention relates to a permanent magnet embedded rotary electric machine with a permanent magnet embedded in a rotor.
2. Description of the Background Art
Conventionally, a permanent magnet embedded rotary electric machine is known which has a rotor having a permanent magnet embedded in a rotor iron core composed of stacked electromagnetic steel sheets, and a stator having an armature winding around the rotor.
As a method for cooling a permanent magnet in such a permanent magnet embedded rotary electric machine, besides a method of dissipating heat by applying cooling oil to the surface of a rotor from outside, there is a method of providing a refrigerant flow passage in a rotor iron core composed of stacked magnetic material sheets as shown in Patent Document, Japanese Laid-Open Patent Publication No 2011-223717.
However, in such conventional permanent magnet embedded rotary electric machines, since a refrigerant is not directly applied to a permanent magnet, there is a problem that the cooling effect is low, so that the output of the electric machine used for an electric power steering apparatus or the like is difficult to be increased.